Add a config option to block "expensive" pages for anonymous users (#34024)

Fix #33966

```
;; User must sign in to view anything.
;; It could be set to "expensive" to block anonymous users accessing some pages which consume a lot of resources,
;; for example: block anonymous AI crawlers from accessing repo code pages.
;; The "expensive" mode is experimental and subject to change.
;REQUIRE_SIGNIN_VIEW = false
```

tests/integration/api_packages_container_test.go

@@ -111,7 +111,7 @@ func TestPackageContainer(t *testing.T) {
 				AddTokenAuth(anonymousToken)
 			MakeRequest(t, req, http.StatusOK)
 
-			defer test.MockVariableValue(&setting.Service.RequireSignInView, true)()
+			defer test.MockVariableValue(&setting.Service.RequireSignInViewStrict, true)()
 
 			req = NewRequest(t, "GET", fmt.Sprintf("%sv2", setting.AppURL))
 			MakeRequest(t, req, http.StatusUnauthorized)